The Reliability of Historical Data

I've been writing up my research on presettlement forests in western New York, and one of the most frustrating things about this work is that there is a huge gap in the data and--obviously--no way to go back and correct it.

The land surveys I work with were done in 1811. Three out of four surveyors used the same sampling methods. But one of them--was he confused? too innovative?--did not collect one of two types of data. Specifically, what surveyors were expected to do was to find the corner of the property lots and then locate the closest tree to that corner. They would write down the species of that tree, its diameter, and where it stood in relation to the corner (distance and compass direction). Then they would also blaze the tree with the lot numbers (carve the numbers into the bark). This information was collected so that whoever bought the property could then go out and identify the boundaries of their land. Unless the tree was struck by lightning and went up in a blaze, this was a fairly reliable way of keeping track of property corners for at least a couple of decades. And it helps forest scientists 200 years later.

But in the surveys I'm using, one surveyor did not record this information at all. Instead he had his team cut posts and set them in the ground at the lot corners. This sounds like a LOT more work than blazing a tree and taking down some notes. Moreover, the posts that he set were of ironwood--a small tree that is hard to cut but rots quickly. Those posts probably didn't stand for even a decade.

This is a common type of problem with historical data. It's full of gaps. It's not entirely reliable. It can't be checked! Or, in the case of historical records, it may have been gathered in a way that is difficult to reconcile with contemporary measures.

I read of an interesting example of using historical records which was recently published in the Journal of Geophysical Research. Woodworth (et al) made use of tidal gauge measurements in the Falkland Islands collected in the mid-19th century by the explorer James Clark Ross. They correlate these with other historical measurements of sea level and with contemporary measures based on satellite altimetry in order to construct a more long-term record of change in sea level.

What this historical data accomplishes is to show that the rate of sea level rise has been accelerating. In historical ecology, too, what the vegetation data show clearly is that there has been rapid change in the last 200 years but only slow changes in forest composition before that.

Historical data is gappy, but it's often good enough to demonstrate a key point.

A Priori, Empirically Confirmed

From an abstract in the 18 June issue of Science:

Space, and events associated with places and spaces, are represented in the brain by a circuitry made of place cells, head directions cells, grid cells, and border cells. These cell types form a collective dynamic representation of our position as we move through the environment. How this representation is formed has remained a mystery. Is it acquired, or are we born with the ability to represent external space? [Articles by Langston et al. and Wills et al.] investigated the early development of spatial activity in the hippocampal formation and the entorhinal cortex of rat pups... A neural representation of external space at this early time points to strong innate components for perception of space. These findings provide experimental support for Kant's 200-year-old concept of space as an a priori faculty of the mind.

Three questions:

1. Would a developmental pathway that is triggered early in a child's experience of the external world, and which is followed in a similar or identical way in all normal people fail to confirm the concept of space as a necessary faculty of the mind?
2. Does this mean that the 1st Critique was referring, all along, to rat minds?
3. Does an a priori concept become stronger with experimental support?

Where are the Girl Mice in Physiology Research Labs?

Dr. Isis explains why the absence of female test subjects is not simply a matter of gender discrimination.

Namely, beliefs about gender have most certainly had a role in female-blindness (unlike gender-blindness, that's when researchers who depend on women to staff their offices--and who may themselves be women--don't notice that their research subjects are not). This can account, in part, for the assumption through most of the twentieth century that heart disease progresses the same in women as in men. The underlying assumption was that the differences between men and women are just the sexy ones. Although we know better now, research on women still progresses more slowly, and when research on women is lacking, the default position is that they must be more-or-less like men.

Dr. Isis says:

"as we interpret published findings, especially as they apply to the treatment of human patients, we have to remember to ask who comprised the cohort and ask if it is appropriate to apply the findings to female patients. Finally, we have to continue to support groups like the Society for Women's Health Research that remind us of a major gap in medical knowledge, appreciate the effect this gap has on public health, and aims to close it."

Tierney and Women in Science

One thing that Tierney did not mention in his NYT article yesterday is a recent Harvard Business Review report, which says that although 40% of the scientists and engineers in the early stages of their careers are women, most of those women (52%) will quit a job due to gender-related issues.

The reasons? A major factor is "macho" work environments that isolate women. Indeed, 63% said they had been sexually harassed. Another factor is job requirements that are incompatible with maternity and family responsibilities. Most of the women who left jobs said that they would return if employers addressed the issues that made the jobs untenable for them. Pace Tierney, it's not the case that those who felt compelled to quit did so because they realized they were misplaced in a science/technology career.

Gender Equity: False Hopes and False Dreams

Over at The Philosophy Job Market blog, Rebecca Kukla gave us a tally on how this year's job market is shaping up along gender lines. According to the hiring announcements that Leiter has posted, and with all the caveats needed for such informal word-of-mouth data collection, only about 19% of the tenure-track jobs have gone to women. (N.B.: The APA has promised to collect accurate job market statistics this year, but the collection and analysis will take some time yet.)

Since women have been earning about 25 to 30% of PhD's in philosophy, this looks like there are some social or structural barriers to the hiring of women.

This observation set off a fusillade of criticisms, both on the PJM blog and on the SWIP list. Among women in philosophy, one concern is that collecting such statistics carries the implicit message that women who do not choose to pursue a tenure-track teaching career are somehow in the wrong.

This appears to me to be a misunderstanding of the meaning of statistics (and see Kate's earlier response to similar worries). Statistics can only give us a picture of a collective. They cannot tell us anything, much less anything normative, about individuals. They can't say that a certain woman should have been hired in a certain department, or that a certain man should not have.

Indeed, these statistics are completely mute about how many people with PhD's in philosophy move into (or try to move into) tenure track jobs. It is entirely appropriate that some people get a degree and use it for some purpose other than university teaching in philosophy departments. Or they use it for no purpose--they go into another field entirely.

The statistics only point out that men are hired into tenure track philosophy jobs at a disproportionate rate. And the best explanation for this, based on reams of social science research, is that there is explicit and implicit sexism in academia.

But if you don't see my point, then perhaps you'll find some solidarity here instead:
"CEO Barbie Criticized for Promoting Unrealistic Career Images."

Pregnancy and Exercise Reprise

With Paula Radcliffe's marathon win fresh in our minds, Gina Kolata has again written on the scary dangers of exercise during pregnancy.

The article begins with an anecdote about an athlete whom Kolata describes as "knowing no bounds." She ran 7-minute miles while pregnant--but without discomfort and without harming her fetus or her own abdominal muscles.

Next, Kolata reviews the research on exercise during pregnancy. Studies consistently show that when women exercise to the level that they find personally comfortable, there are not increased risks to their babies or themselves. She quotes a doctor who reviewed the literature:

We looked at training patterns during pregnancy and postpartum,” Dr. Pivarnik said. “And we asked, ‘Was the amount of training related at all to adverse events?’ The answer was no.

She writes that some of the most common advice given to pregnant women is to keep their

heart rate below 140 beats a minute. That pretty much guarantees you won’t be exerting yourself much. It was in 1985 guidelines set by the American College of Obstetricians and Gynecologists.

The article doesn't mention that this advice was retracted a few years later because it was unsupported by evidence.

Finally, Kolata ends with three anecdotes about women who were all satisfied with their decisions to stop or significantly cut back on their exercise during pregnancy.

There is something strange about this. The evidence cited suggests that there's no problem with vigorous exercise. But practically all the anecdotes (which are what one remembers) are of people who don't follow the evidence. I would like to hear first-person anecdotes that coincide with what the doctors and medical studies say!

Moreover, by citing anecdotes about extremely effective athletes--marathon winners, swimmers of the English Channel, Kolata gives the impression that the only women who would even try to exercise during pregnancy are professionals. I'm no athlete. I consider a 10-minute mile to be an excellent personal pace. But I have never enjoyed running as much as I did while pregnant. My training improved for the first 20 weeks, then I slowed my pace, and I eventually switched to moderate swimming during the last couple of months.

Although Kolata speculates about what might go wrong due to exercise in pregnancy, she doesn't mention even one reason why women would want to exercise. There are many:
1. Moderate and vigorous exercise can reduce morning sickness and nausea.
2. Exercise helps to maintain strength and flexibility. These are certainly required for the later stages of pregnancy and for motherhood.
3. Being engaged in physical activity helps one to focus on one's physical state--thereby increasing awareness of changes and possible problems.
4. Exercise reduces stress and has significant benefits for mental health. It stabilizes mood and increases self-confidence.
5. Exercise helps to regulate appetite and sleep, both of which can be negatively affected during pregnancy.
6. Exercise is a part of many people's routines and identity. There ought to be good cause for relinquishing a routine or a favorite activity, especially when going through other physical, social, and emotional changes.

Feminists should address more vocally the advice and treatment that doctors give to pregnant women and new mothers which limits their activities and choices without any counterbalancing benefit.

Rixa has recently written about feminism and the mainstream medical treatment of pregnancy and birth:

Birth issues are noticeably absent from almost any feminist platform. That's a shame, I think. The National Organization for Women has recently made some statements about birth issues, including a statement against VBAC bans, but otherwise feminism has been oddly silent on the birth side of "reproductive rights."

Pregnancy and Paternalism

The New York Times ran a profile article about Paula Radcliffe, the female winner of yesterday's New York City marathon. The profile is written by Gina Kolata, of the Science and Health section. Because in addition to being the holder of the world record in the women's marathon, Paula Radcliffe has also been pregnant. Imagine that! An athlete AND a Mom!

Just about a century ago, pregnant women (well, pregnant women of a certain class) were cautioned not to exert themselves during pregnancy. Doctors were concerned that work or strain of any sort would stress the fetus. Women were cautioned not to write, not even to think, because using her cognitive powers would divert the woman's reproductive energy away from the babe growing inside of her.

Although our culture no longer has precisely this worry (and most women, including professors, are expected to perform their jobs up until they give birth), there is a residual worry that a pregnant woman's body is not able to sustain physical effort.

The article reports that Radcliffe continued to run while she was pregnant, but only under the close and constant supervision of a doctor. Nonetheless

"People were looking at her as if she were crazy."

Most pregnant women are cautioned by their doctors not to exercise strenuously or, sometimes, moderately or even at all. My OB told me to stop running and to walk instead. I continued to run through most of my pregnancy, as did several other women that I know. One ran until the day before she delivered her baby, and she ran a 10K when he was a couple of months old.

Radcliffe's doctor "allowed" her to keep running but told her to keep her heart rate below a benchmark and had her get extra ultrasound exams. Interestingly, the article also notes

Heart-rate precautions do not have scientific backing.

There is no scientific evidence to speak of concerning pregnancy and exercise. There are no controlled studies and very few epidemiological studies. In the absence of evidence, many obstetricians give out the same advice they were handing to women in the 1800s. At the same time, medical advice concerning exercise for other patients, who often have a real health problem, has changed across the board. Back-ache? Exercise. Arthritis? Exercise. Diabetes? Exercise. Elderly? Exercise. Depression? Exercise.

Given the anecdotal evidence and the new medical context which supports the benefits of exercise (for those who enjoy it, especially), it's hard to see any explanation for the cautions routinely handed out to pregnant women other than paternalism.

What’s natural about natural childbirth?

Jender at Feminist Philosophers has a recent post about natural childbirth. She writes that the literature supporting natural childbirth is too often misleading.

Telling women that if they shop around hard enough for the right midwife, and work hard enough on their relaxation techniques and positions they’ll have a great uncomplicated time is SERIOUS misinformation.

She raises an issue similar to my post earlier this week, where I argued that a general preference for ‘natural’ ecosystems over ‘improved’ or ‘disturbed’ landscapes can be justified empirically but not with metaphysics.

‘Natural’ childbirth can mean many things to different people, from vaginal birth, to a birth without pain medications, to a birth that minimizes interventions, to a home or unassisted birth. Sometimes--perhaps too often, as Jender notes--there is a belief that if labor and birth are allowed to progress in their own time and their own way, then the labor will be less painful and delivery will be uncomplicated. And then, when the labor and delivery are slow or complications do develop, a mother whose goal is natural childbirth could feel disappointed, cheated, or even ashamed, as though she was unable to achieve what “should” be a natural biological function.

But this view entails attaching a prescriptive metaphysics to the concept of ‘natural.’ It is analogous to saying that wilderness should be valued more highly than agricultural fields because wilderness is ‘natural.’ But I like to eat bread and grapes and artichokes! Still, without buying into a flat-rate preference for natural landscapes over cultivated ones, I think we can still justify on empirical grounds why we should look to what is natural to identify the conditions in which humans and other creatures flourish.

Likewise, empirical evidence and some well-accepted criteria for healthful outcomes are what is needed to support natural childbirth and, most importantly, to support educating expectant mothers about the physiological process of birth. A good education would include what sort of pain can be expected and the average duration of active labor (which, for first-time mothers, is 20 hours, more than many practitioners allow before augmenting with pitocin).

When C-section rates rise, so do mortality rates for mothers. Mothers who have had C-sections are more likely to have additional complications, take longer to recover (on average, of course), and are less likely to breastfeed. In addition, they are more likely to have complications with subsequent pregnancies. Other interventions, such as pitocin induction, epidural pain-relief, and electronic fetal monitoring are implicated in poorer outcomes insofar as they contribute to the likelihood of unplanned caesarean birth.

The evidence supports taking steps that are likely to give women more control over birth, more autonomy during labor, and more choice than is usual in US maternity wards. But intending a natural childbirth is certainly no guarantee that labor will progress according to a plan! It would be heartless to deny the necessity and high value of medical interventions when needed, not just for emergencies like placental abruption, but also for pain relief when unexpected pain is harming a mother’s ability to give birth.

Rixa has written recently on what should be done about rising caesaraean rates. She quotes Michael Odent:

The primary objective should not be to reduce the rates of caesareans: it would be dangerous, if not preceded by a first step. This first step should be an attempt to promote a better understanding of birth physiology and particularly a better understanding of the basic needs of women in labour.

A preference for what is natural

So often in what I read and in conversations with students about environmental problems, there is an implicit assumption that what is “natural” is better than whatever has been “disturbed” or “improved” by humans.

Most of the time, I feel that my task is to demand that the speaker think more critically about
1. why we should prefer a natural to an unnatural state since, for example, a world without smallpox seems to be a better world overall;
and
2. whether we can really ever identify a “natural” state, after millennia of human disturbance in most tropical and temperate regions and with the propagated effects of climate change, pollution, and transported species reaching even into apparent wilderness regions.

But to be fair, the shorthand of preferring natural conditions to unnatural ones is very often legitimate. Whether our concern is for human well-being or stability in ecosystems, the natural state is one that has been tested and proved, and the unnatural one has not. The proper justification, then, for this preference for what is natural is empirical evidence, not metaphysics.

Critics of the popular desire for political action on global warming like to point out that there are plenty of people who stand to be better off should their climate grow a little warmer. It will be possible to grow more wheat in Canada, for instance, and the Northwest Passage will become a viable alternative to shipping goods overland or through the Panama Canal. While it’s true that human changes may improve the world for some human goals, the fear is that they will disturb delicate systems with uncertain, and probably unwelcome, results.

A recent report in Science (Araki, Cooper, and Blouin, “Genetic Effects of Captive Breeding Cause a Rapid, Cumulative Fitness Decline in the Wild”, Science 318: 100-103) adds another case to the roster of well-intended interventions with negative long-term implications. It seems that captive breeding and wild release of fish stock may lead to lower reproductive fitness in only a few generations.

The report concludes

The evolutionary mechanism causing the fitness decline remains unknown. We suspect that unintentional domestication selection and relaxation of natural selection, due to artificially modified and well-protected rearing environments for hatchery fish, are probably occurring…To supplement declining wild populations, therefore, repeat use of captive-reared organisms for reproduction of captive-reared progenies should be carefully reconsidered.

This indicates that the study species--steelhead trout--are being domesticated. The alternative to stocking wild populations is to do more (much more) to prevent decline in the first place. This means reducing how many are taken and/or preventing habitat destruction. Neither is easy or popular.

Doubting Research on Genes and Gender

Thanks to Khadimir for asking my thoughts on John Ioannidis' finding that a majority of scientific claims about sex-based genetic differences between men and women are poorly supported. Here's the news report in Science.

The paper, published in JAMA, reviewed published claims about the genetic basis for sex differences in ailments such as hypertension, schizophrenia and heart attacks. Ioannidis found that the claims were, for the most part, overstated or the support for them was undocumented.

The Wall Street Journal quotes Dr. Ioannidis:
"People are messing around with the data to find anything that seems significant, to show they have found something that is new and unusual."

In defense of the peer-reviewed research:
1. Sometimes it does take "messing around with data" to uncover leads for future research.
2. Sometimes the data that would support a claim is not all contained within the published report, but this doesn't mean that the claim is false.
3. The process of peer review and responding to editor's suggestions sometimes stretches claims.
4. That few of the results have been replicated is not surprising. Researchers do not get credit for replicating someone else's findings. The proof comes in using the results as the basis for more research.

What Ioannidis is right to point out:
1. The pressure to publish can lead to stretched claims even when there is no outright fraud, and it can lead to trivial results reported as though they are on a stonger footing than they actually are.
2. In medical research, perhaps replication is more important than in some other areas of science.
3. Philip Kitcher has argued that in areas of science where the results most immediately impact human well-being (such as in medicine), scientists should pay more attention to how "well-ordered" their projects are. Are they pursuing a project only for the sake of getting the next grant? Or does it contribute to what we want and need to know? I take it that part of Ioannidis' concern is that researchers comb their results to find anything that passes the test of statistical significance, regardless of whether or not it tells us something worth knowing. This, then, could explain why so few results are replicated and so few false results are retracted. In this light, what Ioannidis raises is a concern not of truth and falsity but of efficiency.

Finally, I don't think it is particularly suspicious that it is sex-linked claims that were studied--even though sex-linked claims have been the target of feminist critique, e.g. by Anne Fausto-Sterling. The same sort of dynamic is true of other genetic research (and I believe Ioannidis has done similar surveys in epidemiology). However, it is worth thinking about the amount of money that is poured into this sort of research. For some of the diseases studied, such as hypertension, we have quite a lot of understanding about treatment and prevention but still don't treat and prevent for other reasons, such as the shameful lack of access to health insurance in the U.S.

What is experience?

I’ve been thinking a little about what philosophers and scientists mean by “experience.”

Science is empirical; it is based on what can be observed, what can be experienced. This has several important implications. First, explanations are natural, not supernatural. Second, scientific knowledge is based on observed data, not on guesswork, tradition, or sentiment. And third, evidence must be public. In principle, more than one person should be able to observe the evidence; indeed, anyone who is properly positioned to have the experience should have it.

But this is not the only meaning of experience, or even the primary one, in many contexts.

A part of the controversy over evidence-based medicine can be traced to different ideas about the kind of experience that is the basis for medical knowledge. Evidence-based medical practitioners think of medicine as being like a science, for which controlled empirical studies of large numbers of patients provide the best evidence for which treatments work. Others see medicine as being more like a craft that is based primarily on the clinical relationship between doctors and their patients. For them, experience is personal, and some doctors believe that what they have learned from their experience treating patients as distinct individuals cannot be replaced by generic studies.

In an April 2007 New Yorker article by John Colapinto titled “The Interpreter: Has a remote Amazonian tribe upended our understanding of language?”, the linguist Dan Everett claims that members of the Piraha tribe are “the ultimate empiricists.”

Colapinto writes

The tribe embodies a living-in-the-present ethos so powerful that it has affected every aspect of the people’s lives. Committed to an existence in which only observable experience is real, the Piraha do not think, or speak, in abstractions - and thus do not use color terms, quantifiers, numbers, or myths. Everett pointed to the word “xibipio” as a clue to how the Piraha perceive reality solely according to what exists within the boundaries of their direct experience–which Everett defined as anything that they can see and hear, or that someone living has seen and heard. “When someone walks around a bend in the river, the Piraha say that the person has not simply gone away but “xibipio”–”gone out of experience,” Everett said. “They use the same phrase when a candle flame flickers. The light “goes in and out of experience.”

The extreme attitude toward experience of the Piraha points out the limits of empiricism, and why a culture that is empiricist to such a degree could never develop anything resembling modern science, because science is just as dependent on the trustworthiness of testimony as it is on the trustworthiness of direct experience.

On the one hand, our culture, which is a culture thoroughly permeated by science and technology, is resolutely empiricist. On the other hand, we are reliant on information about experiences that are not our own.

I’m reading a book about children and education that quotes ecological psychologist Edward Reed:

There is something wrong with a society that spends so much money, as well as countless hours of human effort—to make the least dregs of processed information available to everyone everywhere and yet does little or nothing to help us explore the world for ourselves.

and

[We are beginning] to lose the ability to experience our world directly. What we have come to mean by the term experience is impoverished; what we have of experience in daily life is impoverished as well.

I have a hard time seeing that what we mean by experience is at fault, or that abundance of information is necessarily a barrier to having first-person, direct experiences.

Although Reed is allied with pragmatists James and Dewey, to hold that our concept of experience (as second-hand, testimonial information about the world rather than direct perception) strikes me as less than pragmatic. Isn't it possible that our easy access to information, and increasingly good and well-vetted information, may serve us in gaining direct, first-hand experience? For instance, if I’m interested in trees, I might look up what trees grow in the forest outside my back door, learn that tulip trees are common and a little about them, and then by going into the forest be able to distinguish tulip trees from other trees by their flower and leaves. Although this is not the same kind of activity as aimless noodling about, I can learn to be a better direct observer by having access to second-hand information.

In the context of childhood education and the value of spending time in nature and time in creative play, then it seems to me that it is not the meaning of ‘experience’ that is at fault but an education system that is relentlessly competitive on many different levels and that relies on simple tests to gauge complex learning. A completely different matter.

Evidence in medicine: Fetal monitoring

A new study has indicated that fetal oxygen monitoring does not improve outcomes during childbirth. The randomized, controlled study was large, involving 14 hospitals and over 5,000 subjects, and the results have been published in an article and editorial in the New England Journal of Medicine. The study had been designed to enroll 10,000 subjects, but the findings were so clear that it was halted early.

The hope behind the technology was that by monitoring both heartrate and oxygen level, obstetricians would be able to discern which babies were truly in an emergency situation, thus lowering the rate of Cesarean sections. That is, the additional monitor, it was hoped, would correct for the failure of heartrate monitoring alone to lower infant mortality rates and the rate of complications such as cerebral palsy. The fetal oxygen monitor will now be discontinued.

This study is important because it was performed before the technology was widely adopted, in contrast to fetal heart monitoring. A number of studies have shown that routine fetal heart monitoring, too, is no better at predicting fetal distress than a trained nurse with a fetoscope, but that it does increase a woman's chance of having a C-section (not to mention that it constrains a woman's movement during labor and that internal monitoring is an invasive procedure for both mother and fetus). Nonetheless, obstetricians have come to rely on fetal heart monitoring, and 85% of births are so monitored. The C-section rate rose again last year to 30.2% of all births, a 46% rate increase in a decade. (An editorial about the shortcomings of fetal heart monitoring, with references, is here.)

Evidence in medicine: Preeclampsia

Again on the theme of pregnancy, the July 24 issue of the New Yorker (not available online) contains an article by Jerome Groopman on the "The Preeclampsia Puzzle."Preeclampsia is characterized by high maternal blood pressure and protein in the urine; it can also cause kidney and liver problems, hemorrhage, and stroke. It affects 5% or more of pregnancies in the US, and globally it is a leading cause of maternal death and of lasting complications for mothers and infants.

The cause of preeclampsia is unknown, and the recommended treatment is delivery of the baby ASAP. Although the complex causal pathways that lead up to many diseases are unknown, it is worth pointing out that there is something special about pregnancy disorders: they are not well-studied.

There are several reasons for this. Fetuses cannot consent to participate in clinical trials. Pregnant women, understandably, are not motivated to take on risks to their pregnancy and fetus in order to test new drugs and therapies. Moreover, in some cases, as in preeclampsia, the best available treatment is to deliver the baby, which precludes further testing or treatment in utero.

But if pregnancies are so valuable, shouldn't it be possible to overcome some of these obstacles? Perhaps by running larger trials which permit deeper statistical inferences. But large trials take funding, and this is what the New Yorker article has to say:

Among medical researchers, obstetrics is often regarded as a dead end. "An enterprising young physician-researcher who seeks to make his [sic] name in a field faces huge hurdles if he wants to work with pregnant women"..."Our ability to truly understand what goes on in the fetus is poor," he [Sachs] said. "You can't predict physiologically how a fetus is going to respond to some treatment given to the mother. So people are very hesitant to do this kind of research, and the committees that protoect human subjects are, by and large, gun-shy"..."The only large clinical trials that have been going on involve innocuous treatments, like antioxidants, low-dose aspirin, or supplements like calcium," Sachs said.

Disorders of pregnancy receive relatively little research from the federal government, even though they exact a considerable medical and financial toll.

But it is not just studies of treatments that cannot get off the ground. Even descriptive studies and the development of registries for tracking diseases of pregnancy and post-delivery outcomes are lacking. As with gestational diabetes, the exact rates of preeclampsia in the US are not known, nor are the contributing factors well understood.

The culture of obstetrics is not oriented toward identifying causes that would permit prevention. This is also a relevant topic for feminist bioethics. As Laura Purdy has argued in her article, "What feminism can do for bioethics," bioethicists can and should take on advocacy tasks that shift the way that research is ordered and prioritized.

HPV Vaccine vs. Pap Smears? What's wrong here?

Thanks to Evelyn for inviting me to contribute. I was working on a more theoretical post about feminist philosophers of science and what, if anything, they should want to say about the issue of scientific realism/antirealism and I hope to post something on that later, but I had a negative reaction to an essay, “A New Vaccine for Girls, but Should It Be Compulsory?”, by Roni Rabin on the opinion page in the NYT today and so I wanted to say something in response to it.

First, the parts I think are right. Yes, we should be careful when advocating compulsory health care. Yes, we should make it possible for all women to get routine Pap smears. Both of these points seem right, but this argument is constructed in such a way that one might walk away thinking that Pap smears will prevent cervical cancer and so there is really no need for this vaccine, end of story. But this is disingenuous and misleading. It isn’t Pap smears that prevent cervical cancer. Pap smears alert us to the need to proceed to other procedures that can prevent cervical cancer. So they are necessary but not sufficient. Since the current vaccine prevents only the four of the most common forms of HPV (which account for 70% of cervical cancers), it is not sufficient to prevent cervical cancer either and so does not eliminate the need for Pap smears. The lesson here should be that this is not an either/or situation; the ideal is both vaccine and Paps.

There’s another concern that I have though. Rabin focuses on the number of deaths from cervical cancer (relatively low) and notes that these have been and can continue to be reduced though Pap smears as part of routine health care for women. True, but the medical cost of HPV should not be weighed only in terms of deaths. Women whose immune systems do not automatically clear the virus will need more frequent Pap smears (every three or 6 months rather than once a year) and may also need more invasive treatment to remove dysplasic cells. These treatments, such as the LEEP procedure, while done on an outpatient basis, can be uncomfortable and expensive. Repeated incidents of “bad” Pap results can mean multiple procedures. The jury is out on whether and if so to what extent repeated procedures compromise cervical competence and so put future pregnancies at risk. (Samson SL, Bentley JR, Fahey TJ, et al: The effect of loop electrosurgical excision procedure on future pregnancy outcome. Obstet Gynecol 2005 Feb; 105(2): 325-32.) So while certainly the most frightening cost of HPV is cervical cancer it is not the only cost.

Given a political climate in which it has already been suggested that this vaccine should not be offered because it will encourage sexual promiscuousness, I think we need to be very clear about just what and are not the consequences of advocating particular public health policies. While I fully agree that it should be a public health priority to ensure that all women are informed and able to get Pap smears as part of their routine health care, I do not think we should be seeing this as an alternative to making use of a vaccine that can cut out the possibility of contracting the forms of HPV which result in 70% of cervical cancers. This strikes me as another case of false economic reasoning about health care that occurs in a society that does not have health care as a priority for all of its citizens.

General information about the vaccine from the CDC here.

Evidence in medicine: Length of pregnancy

Several doctors, midwives, and pediatricians have said to me recently that they practice "evidence-based medicine," unlike many of their colleagues.

Evidence-based medicine is, presumably, about practicing using interventions and techniques which have been supported by empirical, clinic-based evidence—and avoiding techniques which are untested or have failed empirical tests. As one advocate explains,

The practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical expertise from systematic research....By best available external clinical evidence we mean clinically relevant research, often from the basic sciences of medicine, but especially from patient centred clinical research into the accuracy and precision of diagnostic tests (including the clinical examination), the power of prognostic markers, and the efficacy and safety of therapeutic, rehabilitative, and preventive regimens (D.L. Sackett et al., British Medical Journal, 1996).

What alternatives are there to basing medical practice on evidence?
Theory-based medicine?
Ideology-based medicine?
Tradition-based medicine?
Sentiment-based medicine?


In the face of the obvious, there is indeed much of standard medical practice that remains empirically unsupported. To take an example, the standard formula for the expected length of pregnancy is calculated according to Naegele's Rule, which places the due date at 40 weeks from the start of the last menstrual period. This guideline was calculated in 1838 by German physician Franz Carl Naegele based on the belief that a term pregnancy ought to last exactly 10 lunar cycles (a nice, round number). It was not based on empirical data.

Indeed, empirical studies have shown that length of pregnancy is influenced by previous number of births, age, race, and other factors. So, for instance, the duration of pregnancy for white women with no previous births averages 7 days longer than Naegele's rule predicts (Mittendorf, American Journal of Obstetrics and Gynecology, 1990 and 1993).

Where is the harm in this? Standard practice for many obstetricians is to recommend labor induction—which increases risks to mother and baby—in the 41st week of pregnancy. This is the point at which, at least for first time mothers, only half would be expected to go into labor naturally. The most current figures I could find (from 2002) show that induction rates exceeded 50% for some hospitals, and anecdotal evidence is that they are now even higher.